Ubuntu login control

How to view login information

Basically Ubuntu saves all the log information in a log file inside /var/log/auth.log which you can access manually or use the following command in the terminal.

sudo less /var/log/auth.log 

How to disable guest login

In the file /etc/lightdm/lightdm.conf add the following line

allow-guest=false

If you are using a newer version of Ubunutu, try the file /usr/share/lightdm/lightdm.conf.d.

Make sure to restart the system to take effect.

In order to allow guest login again, remove the code line from the file.